750/1100 Hybrid Gearbox?

[Danm54]

I know you can fit the 750 w gearbox to the 1100 cases but can you just swap say 1st and 2nd from the 750 into the 1100?

 

I'm on a quest for 200mph and the 1100 will only do it with tall sprocket gearing.

Thinking that swapping in a 750 gear or 2 will give it an easier time pulling away.

 

Thoughts?

[Duckndive]

I doubt it as the 750 - 6 speed gears are narrower

[Danm54]

Can they be shimmed though?

 

I have an 1100 gearbox but nt a 750 to compare them.

[Gixer1460]

10 hours ago, Danm54 said:

I know you can fit the 750 w gearbox to the 1100 cases but can you just swap say 1st and 2nd from the 750 into the 1100?

I'm on a quest for 200mph and the 1100 will only do it with tall sprocket gearing.

Thinking that swapping in a 750 gear or 2 will give it an easier time pulling away.

Thoughts?

I'm a bit confused - speed is a function of HP v's Drag and as a lot of hp is needed to do 200mph, it's easy enough to get a bike rolling with a less than optimal 1st or 2nd gears. Superstreet bikes use std (worked on) gearboxes and hit 200mph in the quarter - its the clutch that takes the grief. Are the 750 gears so significantly different and can you avoid a large step to 3rd if it works at all?

[Danm54]

I've not worked it out but a friend has and there is a benefit to use 1st from the 750 box. Not sure how much though.

 

I'll be trying it with the sprockets first obviously but I may as well look into the possibility of swapping gears to see if it can be done or not.

 

If it's not possible/worth the effort I'll be buying spare clutch plates...

[dupersunc]

Playing about with gearing commander. https://www.gearingcommander.com/

GSXR 1100 wn geared for 201mph.  180/60 tyre and 16/39 final drive @10500rpm

Standard.                                   1st  76.9 mph at 10500.    2nd 115.4 mph at 10500

750 ratio in in 1100 box          1st 72.8 mph at 10500     2nd 101.4 mph at 10500.

 

So by going to the trouble of swaping gears, you get a 1st gear that is 4mph shorter, and horrible rev drops between 1st,2nd and 3rd gears.  Further more 1st and 2nd are the most stressed gears so fitting the narrower 750 versions is the last thing to do with a heavily tuned motor if you want the gears and shafts to live.

            

[Danm54]

That settles it then!

 

I'd looked at gearing commander but only used a 180/55 tyre, using a 60 bumps the speed up a good amount.

 

Using the buell rear wheel the smallest rear sprocket I can use is 42t, I've got a 17t on the front but can't find an 18t, don't know if it'll fit either.

[Gixer1460]

On a GSXR based cases, a 18T front won't fit - many have tried!

Edited May 28, 2019 by Gixer1460

[Jaydee]

4 hours ago, Danm54 said:

I've got a 17t on the front

Just out of interest, what pitch was the front sprocket and did it clear everything or did you have shave a little off?

[Danm54]

33 minutes ago, Jaydee said:

Just out of interest, what pitch was the front sprocket and did it clear everything or did you have shave a little off?

Its a 530 sprocket, went straight on without any problems

[Duckndive]

4 hours ago, Gixer1460 said:

On a GSXR based cases, a 18T front won't fit - many have tried!

If it’s the clutch push rod is the issue then you need a right hand side cable clutch cover....don’t know if they fit water boilers 

[Gammaboy]

 

5 hours ago, Duckndive said:

If it’s the clutch push rod is the issue then you need a right hand side cable clutch cover....don’t know if they fit water boilers 

They don't, but the 750WN has a cable clutch.

[Gixer1460]

Now that's just cheating but I understand the chain hits the cases also with an 18T - a 17T with a 532 chain was pretty close for me.

[Madb]

I would doubt very much the 750 gears would hold up in a 200mph behemouth. But the good news is the 750 clutch case will fit the eleven but you would need a 7 mm(i believe) spacer made to clear the larger clutch on the 11. Not sure how the the clutch pinion would fit tho. I have not done it but someone has on the old forum.

[Fula28]

Dan Stu has build one of these while back, skinney 750 gears in. 11 motor loads of messing about and fettling ,but of course it does work. Just not as strong.

Edited June 4, 2019 by Fula28